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What is it? Overview Usage Side Effects and Warnings

What are Antihistamines?

Possible side effects of antihistamines include:

  • Sedation
  • Drying of secretions, which impairs their clearance and may lead to complications (such as sinusitis, otitis, and pneumonia)
  • Retention or difficulty passing urine
  • Rashes
  • Dizziness
  • Headache
  • Indigestion
  • Constipation
  • Anemia

Talk to your doctor before taking these medications if you have the following conditions, which can be made worse by the side effects of antihistamines:

  • Urinary problems due to an enlarged prostate gland
  • Glaucoma
  • Breathing problems

Possible side effects of over-the-counter antihistamines include:

  • Drowsiness (Claritin and Zyrtec are non-sedating)
  • Slowed reaction time
  • Dry mouth

Possible side effects of prescription antihistamines include:

  • Drowsiness
  • Lightheadness
  • Blurry vision
  • Change in ability to think clearly
  • Dry mouth, nose, or throat
  • Gastrointestinal upset, stomach pain, or nausea
  • Increased appetite and weight gain
  • Thickening of mucus
  • Increased effects in people with kidney disease due to slower removal from the body